This prospective observational pilot study evaluates agreement between Ultrasound Cardiac Output Monitor (USCOM) measurements and transthoracic echocardiography-derived hemodynamic parameters in pediatric patients under standardized general anesthesia prior to surgical incision. Under stable hemodynamic and ventilatory conditions, suprasternal Doppler-derived velocity time integral (VTI), stroke volume (SV), cardiac output (CO), stroke volume variation (SVV), and aortic valve area (AVA) are obtained sequentially with USCOM and echocardiography within a short time window without changes in ventilation, anesthetic depth, positioning, fluid therapy, or vasoactive support. Agreement is assessed using correlation and Bland-Altman analyses.